Recently, there has been a demand for deodorization and sterilization by generating a trace amount of ozone as well as negative ions with an ion generator. However, high levels of ozone have germicidal activities which are too high and can be harmful to the human body. The amount of ozone thus must be controlled to an adequate level.
There is a conventionally known ion generator of this type, which has been described in Patent Document 1. In the ion generator, to minimize generation of ozone, the whole surface of a ground electrode provided on an insulation substrate is covered with an insulating resin. The ion generator thus cannot generate a trace amount of ozone as required.
Patent Document 2 has described an apparatus for generating a steady amount of ozone by maintaining a steady power source voltage applied to a high-voltage generator using an amplitude restricting means to arbitrarily restrict the voltage amplitude of a commercial electric power supply. However, the apparatus generates ozone only, and hardly generates a trace amount of ozone.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2005-63827
Patent Document 2: Japanese Unexamined Patent Application Publication No. 07-6857